This is a study of the health of 766 storage battery workers in six plants and of the diagnostic value of several laboratory tests. The proportion of workers with early plumbism, classified by atmospheric exposure to lead, rises from 4 per cent for men exposed to less than 0.74 mg. of lead in 10 cubic meters of air to 54 per cent for men exposed to more than 3 mg. of lead per 10 cubic meters of air. There are no important time trends. Nine men had a combination of clinical and laboratory signs that warranted a diagnosis of incipient plumbism. No disabling plumbism was seen. Relatively few men complained of ill health, and there was only a small correlation between the frequency of a complaint and the concentration of lead in the atmosphere to which the workers were exposed. Each of the 9 men had a blue or metallic